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Mol Biochem Parasitol. 2015 Jun;201(2):85-9. doi: 10.1016/j.molbiopara.2015.06.002. Epub 2015 Jun 22.

Biochemical characterization of FIKK8--A unique protein kinase from the malaria parasite Plasmodium falciparum and other apicomplexans.

Author information

1
Dept of Molecular Genetics, University of Toronto, Canada; Structural Genomics Consortium, University of Toronto, Canada.
2
Dept of Pharmacology, Yale University, United States.
3
Structural Genomics Consortium, University of Toronto, Canada.
4
Hospital for Sick Children, Canada.
5
Structural Genomics Consortium, University of Toronto, Canada; Toronto General Hospital Research Institute, Canada. Electronic address: raymond.hui@utoronto.ca.

Abstract

FIKKs are protein kinases with distinctive sequence motifs found exclusively in Apicomplexa. Here, we report on the biochemical characterization of Plasmodium falciparum FIKK8 (PfFIKK8) and its Cryptosporidium parvum orthologue (CpFIKK) - the only member of the family predicted to be cytosolic and conserved amongst non-Plasmodium parasites. Recombinant protein samples of both were catalytically active. We characterized their phosphorylation ability using an enzymatic assay and substrate specificities using an arrayed positional scanning peptide library. Our results show that FIKK8 targets serine, preferably with arginine in the +3 and -3 positions. Furthermore, the soluble and active FIKK constructs in our experiments contained an N-terminal extension (NTE) conserved in FIKK8 orthologues from other apicomplexan species. Based on our results, we propose that this NTE is an integral feature of the FIKK subfamily.

KEYWORDS:

Apicomplexa; Cryptosporidium; FIKK kinase; Kinase

PMID:
26112892
PMCID:
PMC4576209
DOI:
10.1016/j.molbiopara.2015.06.002
[Indexed for MEDLINE]
Free PMC Article

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